Zipper tape for a bag and method of producing the same

ABSTRACT

A zipper tape is provided which can freely be used regardless of whether the zipper tape is made from a polypropylene-based resin or a polyethylene-based resin and also on which letters can be printed or any color can be given thereto. A method of producing the zipper tape with high productivity by means of extruding male strips and female strips in rows in a batch is provided. The zipper tape ( 2 ) with the mating section ( 3 ) (the male strip ( 3   a ) and the female strip ( 3   b )) formed thereon has a three-layered structure comprising the heat-insulating film ( 6 ) as an intermediate layer, the thermally fused film ( 7 ) thermally fused and bonded to one side of the heat-insulating film ( 6 ) of the bag ( 5 ), and the thermally fused film ( 8 ) for formation of a mating section bonded to another side of the bag ( 5 ). The male strips ( 3   a ) and female strip ( 3   b ) for forming a mating section together are extruded from the miscellaneous extrusion molding machine ( 101 ) onto a surface of the thermally fused film ( 8 ) for forming a mating section in rows in the state where adjoining male and female strips form pairs respectively and are thermally fused and bonded to the base tape. Then the base tape is cut along each strip with the adjoining male strip ( 3   a ) and female strip ( 3   b ) mated with each other to form the mating section ( 3 ), and is wound up to provide a product. Letters, marks, or colors are printed on or given to the mating sections ( 102 ) and ( 104 ) on the base tapes ( 101 ) and ( 103 ) respectively.

FIELD OF THE INVENTION

[0001] The present invention relates to a method of producing a zippertape agglutinated in use to a bag for packaging as well as to a zippertape produced by the production method, and more specifically to azipper tape having a mating section comprising a male strip and a femalestrip and a method of producing the zipper tape.

BACKGROUND OF THE INVENTION

[0002] Bags for packaging which have a zipper tape closure are verypopular. These bags can easily and repeatedly be opened and closed. Itis generally expected in the market that a bag with a zipper tape willbe used more and more in the future.

[0003] The conventional type of zipper tape is generally based on apolyethylene system or a polypropylene system, and a male strip and afemale strip forming a pair extending in a row and used to form a matingsection. The strips are integrally formed on a tape, and the tape is cutin use along a center line thereof to provide a slender section with amale strip and that with a female section. When this zipper tape isagglutinated in use to a bag 1 for packaging as shown in FIG. 1, thecross section taken along the line A-A in the figure is as shown in FIG.2(A), and a tape section 4 with a male strip 3 a and a female strip 3 bformed thereon is based on a polyethylene system when a resin used foran innermost layer 5 of a bag 1 for packaging is a polyethylene-basedone, while the tape section 4 is based on a polypropylene system whenthe resin for the innermost layer 5 is a polypropylene-based one.

[0004] However, the conventional type of zipper tape has the defects asdescribed below.

[0005] a) At first, when the zipper tape 2 is produced by means ofmiscellaneous shape extrusion molding, the male strip 3 a and the femalestrip 3 b are respectively formed on the tape section 4 in an integratedstate therewith as shown in FIG. 2(A), and in this production method, itis impossible to mold a plurality of male strips and a plurality offemale strips simultaneously in batch, and the two types of strips areformed only as a pair by means of extrusion molding, so that theproductivity is low.

[0006] b) When the zipper tape 2 is agglutinated to the bag 1 forpackaging, when the innermost layer 5 of the bag 1 and the tape section4 of the zipper tape 2 are jointed to each other by loading a pressureand heating the jointed section from the outside as shown in FIG. 2(A),as there is the risk that the tape section 4 itself may be fused thereis no way but to make the thickness of the tape section 4 larger.

[0007] Because of the requirement described above, when a pressure andheat are applied from the outside for making side seals 1 a, 1 b of thebag 1 for packaging as shown in FIG. 2(B), the mating section 3 and thetape section 4 form together a fused resin block 3′, 4′, and the sectionexpands, so that the pressure and heat required for sealing must bestrong, which causes other sealed sections to be heated excessively. Onthe contrary, when the pressure and heat used for sealing are weak, theresin block 3′, 4′ is not fully fused such that pin holes are easilygenerated therein.

[0008] d) In the zipper tape 2 comprising the mating section 3 made froma polyethylene-based resin and the tape section 4, as the innermostlayer 5 of the bag 1 for packaging is thermally fused only thepolyethylene-based bag, so that the zipper tape 2 can not be used for abag made from a polypropylene-based resin. On the other hand, the zippertape 2 made from a polypropylene-based resin can not be used for the bag1 made from a polyethylene-based resin, and therefore the zipper tape 2must be selected according to a material used for forming the innermostlayer 5 of the bag 1.

[0009] Improved types of zipper tapes have been disclosed for thepurpose to solve the problems as described above. As the mostrepresentative technology, there is the technology in which aheat-insulating film 6 having a melting point higher than that of thetape section 4 is laminated on the tape section 4 of the zipper tape 2and further a film 7 for thermal fusion having a melting point lowerthan that of the heat-insulating film 6 is laminated on theheat-insulating film 6 (Japanese Patent No. 1908600). Namely, in thezipper tape 2, which is applied to the bag 1 for packaging shown in FIG.1, the cross section A-A is as shown in is enlarged form in FIG. 3(A),while the cross section A′-A′ is as shown in its enlarged form in FIG.3(B).

[0010] With this improved type of zipper tape 2, some of the problems inthe conventional technology have been solved, but the following ones arestill left unsolved.

[0011] e) When the zipper tape 2 is produced by means of themiscellaneous shape extrusion molding, the male strip 3 a and the femalestrip 3 b are formed integrally on the tape section 4 respectively, sothat there is no way but to form the two types of strips in a pair andin a row, so that the productivity is not improved.

[0012] f) When the innermost layer 5 of the bag land the thermally-fusedfilm 7 of the zipper tape 2 are pressed to each other and heated forsealing, the risk that the tape sections 4 facing to each other arethermally fused to each other is evaded because of the presence of theheat-insulating film 6 as shown in FIG. 3(A), and this improvementadvantageously makes it possible to reduce the total thickness of thetape section 4, heat-insulating film 6, and thermally fused film 7 downto about 100 P.

[0013] g) When the side seals 1 a, 1 b are made in the bag 1, thethickness of the fused resin block 3′, 4′, where the mating section 3and the tape section 4 are integrated to each other, is reduced inproportion to the reduced thickness of the tape section 4 as shown inFIG. 3(B), but the reduction in thickness is still insufficient.

[0014] h) In a case of the zipper tape 2 made from a polyethylene-basedresin, also the thermally fused film 7 and the innermost layer 5 of thebag 1 must be made from the polyethylene-based resin, and further in acase of the zipper tape 2 made from a polypropylene-based resin, alsothe thermally fused film 7 and the innermost layer 5 of the bag 1 mustbe made from the polypropylene-based resin, and this technologicallimitation still remains unsolved.

[0015] i) In the conventional type of zipper for a bag, two sheets ofbase tapes to be sealed on an inner surface of the bag, and the malestrip and the female strip respectively formed on this base tape areintegrally formed by an extrusion molding machine.

[0016] Because of this requirement, when it is desired to give aspecific color to the zipper tape for the purpose to indicate that thezipper tape is attached to inside of an upper open section of the bag orto make the zipper tape colorful, it is necessary to add a coloringmaterial to a resin used as a material for the tape and to extrude thecolored resin from the extrusion molding machine.

[0017] j) For the reason described above, it is possible to give aspecific color to the zipper tape as a whole, but it is impossible togive a color only to the male and female strips, nor to give differentcolors to the mating section and base tape respectively, and thereforewhen designing a bag with a zipper, options in designing the zippersection are disadvantageously limited as compared to those allowable inother sections.

[0018] k) Further, once the zipper tape has been set in an upper opensection of a bag, only a surface of the base tape and the mating sectioncan directly be checked visually, and it is impossible, because of thepresence of the mating section, to print on the zipper tape an alertingmessage such as, for instance, that “If the zipper tape color has notchanged to blue, please check and confirm again that the zipper tape hascompletely be closed” for alerting a user to check whether the matingsection has been completely closed. It is desired to print this type ofalerting message there.

OBJECT OF THE INVENTION

[0019] The present invention was made in the light of the circumstancesas described above, and it is a first object of the present invention toprovide a zipper tape with the large width and having a structureallowing formation of a plurality of pairs of a male strip and a femalestrip each pair extending in a row on the zipper tape and a method ofproducing the zipper tape.

[0020] It is a second object of the present invention to provide azipper tape making it possible to reduce a fused resin block, which isgenerated at the mating section when side sealing for the bag is made,as much as possible to prevent generation of pin holes therein and alsoto ensure the provision of a good appearance of the bag and also toprovide the method of producing the same.

[0021] Further it is a third object of the present invention to providea zipper tape compatible with an innermost layer of a bag regardless ofwhether the innermost layer is made from a polypropylene-based resin ora polyethylene-based resin and also capable of eliminating the necessityof selecting a zipper tape made from the same material as that used foran innermost layer of the bag and also to provide the method ofproducing the zipper tape.

[0022] It is a fourth object of the present invention to provide azipper tape for a bag allowing printing of any letter and figure or thelike with any color on a surface of the base tape.

[0023] It is a fifth object of the present invention to make it possiblefor a user of a bag to visually determine that a zipper tape has beenfitted to inside of an upper open section of the bag by printing thereona remark indicating presence of the zipper tape or giving any specificcolor to the zipper tape.

[0024] It is a sixth object of the present invention to improvecommercial value of a product packaged in a bag for the purpose tocontribute to increase of sales in the market by making it possible tomake a design of a surface of the bag more colorful especially in thesection where the zipper tape is fitted to the bag.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is an explanatory view showing a bag with the conventionaltype of zipper tape fitted therein;

[0026]FIG. 2(A) is a cross-sectional view taken along the line A-A;

[0027]FIG. 2(B) is a cross-sectional view taken along the line A′-A′;

[0028]FIG. 3(A) is a cross-sectional view showing a bag using theconventional type of zipper tape consisting of three tape sections;

[0029]FIG. 3(B) is an explanatory view showing a resin block in a sideheat seal section;

[0030]FIG. 3(C) is an explanatory view showing the state in which pinholes have been generated where the tape section is off from the regularportion in the side seal section;

[0031]FIG. 4(A) is a cross-sectional view showing a portion of a bagwith a zipper tape according to the present invention fitted therein,the portion of the bag corresponding to the section indicated by theline A-A in FIG. 1;

[0032]FIG. 4(B) is an explanatory view showing a resin block in the sideseal section corresponding to the section indicated by the line A′-A′ inFIG. 1;

[0033]FIG. 5(A) is a cross-sectional view showing a portion of thezipper tape with a zipper tape according to the present invention usedtherein, the portion of the bag corresponding to the portion indicatedby the line A-A in FIG. 1;

[0034]FIG. 5(B) is an explanatory view showing the state where the tapesection is off from the regular position in the side seal sectioncorresponding to the section indicated by the line A′-A′ in FIG. 1;

[0035]FIG. 6 is a flow diagram showing the method of producing a zippertape according to a fourth embodiment of the present invention;

[0036]FIG. 7 is an explanatory view showing a miscellaneous shapeextrusion molding machine;

[0037]FIG. 8 is an explanatory view showing a slitter section;

[0038]FIG. 9 is an explanatory view showing the zipper tape according tothe present invention;

[0039]FIG. 10 is an explanatory view showing the state in which thezipper tape is fitted to inside of an open section of a bag;

[0040]FIG. 11 is an explanatory view showing the state in which an opensection of a bag with a zipper had been closed by means of heat sealing;

[0041]FIG. 12 is an explanatory view showing a method of producing thezipper tape according to the present invention;

[0042]FIG. 13 is an explanatory view showing a method of producing azipper tape having a mating section with different colors according tothe present invention; and

[0043]FIG. 14 is an explanatory view showing the state in which a malemating section and a female mating section are formed by using differentextrusion molding machines respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] A first different point of a zipper tape 2 according to thepresent invention from the improved type of zipper tape 2 describedabove is that a male strip 3 a and a female strip 3 b on the zipper tape2 are, different from that in the conventional technology. According tothe invention, male strip 3 a and female strip 3 b are not molded in theintegrated state with a fused film 8 for forming a mating section asshown in FIG. 4(A). Also, a base tape including the fused film 8 forforming a mating section is previously produced, then only the malestrip 3 a and female strip 3 b are extrusion-molded by a miscellaneousshape extrusion molding machines. The male and female strips 3 a and 3 bare then fused and bonded at 8 a to a surface of the fused film 8 forformation of a mating section respectively.

[0045] The reason for the employment of the production sequence asdescribed above is based on the fact recently discovered by the presentinventors that, when the zipper tape 2 is fitted to the inside of anopen section of the bag 1 and side seals 1 a, 1 b are made similar tothat as shown in FIG. 1, by processing, different from the conventionaltechnology, only the mating section 3 into the fused resin block 3′ bymeans of applying a pressure and heat thereto for sealing as shown inFIG. 4(B), the size of the fused resin block 3′ can be minimized. Withthis there is a prevention of the generation of pin holes and inaddition the finishing of the bag can be further improved. Thisinvention was made also based on the fact found by the present inventorsas a result of examination on the productivity that, when the zippertape 2 is formed by miscellaneous shape extrusion molding, differentfrom the conventional technology, in which the male strip 3 a and femalestrip 3 b each integrated with the tape section 4 are extrusion-moldedonly in a pair and in a row, by forming only the mating section 3 bymeans of miscellaneous shape extrusion-molding, then it is easy to givea desired form to the mating section 3 and in addition a plurality ofpairs each of the male strip 3 a and female strip 3 b can beextrusion-molded in rows simultaneously.

[0046] Further the present invention is based on the fact that theproductivity is substantially improved by making the mating sections 3of the male strip 3 a and female strip 3 b by means of miscellaneousshape extrusion-molding respectively, fusing and bonding the matingsections 3 to a large-width film consisting of at least three layerspreviously laminated, slitting the male strips 3 a and female strips 3 bin the longitudinal direction after the strips are cooled to mate malestrips with female strips one by one respectively to form the zippertapes 2, and by winding the zipper tapes 2.

[0047] Another important technological factor of the present inventionrelates to the choice of at least resins used for the thermally fusedfilm 7 and thermally fused film 8 for formation of a mating section eachconstituting the three-layered structure of the zipper tape 2 consistingof the thermally fused film 7 fused and bonded to an innermost layer ofa bag, the heat-insulating film 6, and the thermally fused film 8 forformation of a mating section.

[0048] Namely, in the conventional technology, the innermost layer of abag for packaging is made from either a polyethylene-based resin or apolypropylene-based resin, and likely the mating section 3 is also madefrom either one of the two types of resins above. In a case of themating section 3 made from a polyethylene-based resin, as shown in FIG.2 and FIG. 3, it is preferable from the view point of fused resin blocks3′, 4′ generated in the side seal sections 1 a, 1 b of the bag 1 thatthe polyethylene-based resin is as soft as possible. In that case,however, also the tape section 4 is formed in the integrated state withthe mating sections, and the tape section 4 is also made from the sameresin as that used in the mating section, and if the innermost layer 5of the bag 1 is made from a polypropylene-based resin, the tape sectionis not thermally fused and boded to the innermost layer 5 of the bag 1.This is clearly understood from FIG. 2(A). In FIG. 3(A), if thethermally fused film 7 is made from a polypropylene-based resin, itseems that fusion bonding of the thermally fused film 7 to apolypropylene-based resin bag 1 with the innermost layer 5 made from apolypropylene-based resin would be possible, but when the side seals 1a, 1 b are made in the bag 1, if the opposing tape sections 4 are offfrom the regular positions, the tape section 4 made from apolyethylene-based resin directly contact the innermost layer 5 of thepolypropylene-based resin of the polypropylene-based resin bag 1 asshown in FIG. 3(C), and fusion bonding can not be performed in thedirectly contacting section 4 a with pin holes generated therein, sothat the polyethylene-based resin tape section 4 can not be used for thepolyethylene-based resin bag 1. Even when the mating section 3 is madefrom a polypropylene-based resin, it can not be used for thepolyethylene-based resin bag 1 for the same reason as described above.

[0049] For the reasons as described above, a second technological factorof the present invention based on the first basic feature is therequirement to produce all of the mating section 3, the thermally fusedfilm 8 for formation of the mating section to which the male strip 3 aand female strip 3 b forming together the mating section 3, and thethermally fused film 7 to be fused and bonded to the inner most layer 5of the bag 1 with the same material. Namely, the formation with either apolypropylene-based resin or a polyethylene-based resin is according towhether a resin-made film corresponding to the innermost layer 5 of thebag 1 is made from a polypropylene-based resin or a polyethylene-basedresin.

[0050] In addition, specific applications must be taken intoconsiderations for the same technological reason. When a pharmaceuticalcomponent having a higher permeability such as an anti-inflammatoryanalgesic agent is packaged inside a bag with a zipper, usually a filmmade from any of ethylene/acrylic acid copolymer (EAA) resin,ethylene/metacrylic copolymer-based metal ion bridged resin (ionomer),and ethylene/metacrylic acid copolymer resin (EMAA) is used for theinnermost layer 5 of the bag 1. Such materials as a packaging materialwhich can prevent permeation of a pharmaceutical component therethroughand can prevent a resulting reduction thereof.

[0051] Therefore, also in the zipper tape 2, it is necessary to use thesame resin as that is used for the thermally fused innermost layer 5 ofthe bag 1 as a material for at least the thermally fused film 7 amongthe thermally fused film 7 to be fused and bonded to the innermost layer5 of the bag 1, the thermally fused film 8 for formation of the matingsection, and the mating section 3.

[0052] As for the heat-insulating film 6, this heat-insulating film 6 isnecessary, when sealing is performed by applying a pressure and heatfrom outside of the bag 1 with the zipper tape 2 inserted between theinnermost layers 5 of the bag 1 during the bag production process. Thisprevents the opposing thermally fused tapes 8 each for formation of amating section from being thermally fused and bonded to each other asshown in FIG. 4(A). Further, this prevents the fused resin block 3′ frombeing crushed under stable conditions by the application of a pressureand heat from the outside when side seals 1 a, 1 b of the bag 1 are madeas shown in FIG. 4(B). A heat-resistant stretching film such as thebiaxial stretching polyester film or biaxial stretching nylon film ispreferable as a material for the heat-insulating film 6. Any type offilm may be used so far as the film can satisfy the requirement for heatinsulation.

[0053] A third technological factor of the present invention is based ona new technology according to the present invention for selection of aresin to be used for the thermally fused film 7 to be fused and bondedto the innermost layer 5 of the bag 1 and the selection of a thermallyfused film 8 for formation of a mating section to fuse and bond themating section 3.

[0054] Namely, in the construction of FIG. 4(A), it is necessary toselect a polypropylene-based resin or a polyethylene-based resin as amaterial for the thermally fused film 7, which is to be fused and bondedto the innermost layer 5 of the bag 1, according to whether a materialused for the innermost layer 5 of the bag 1 is a polypropylene-basedresin or a polyethylene-based resin (this is not different from theinvention described above. However, an olefin-based film comprising aresin in which, in addition to the polypropylene-based resin andpolyethylene-based resin, an olefin-based resin such as polybutene or apolystyrene-based resin is mixed as a third component may be provided.As an alternative, a resin in which, in addition to the ethylene acetatevinyl copolymer resin and a polyethylene-based resin, an olefin-basedreformer is mixed therein and is used as a third component as a materialfor the thermally fused film 8 for formation of a mating section to befused and bonded to the mating section 3.

[0055] As the olefin-based film can advantageously be thermally fusedand bonded to either a polypropylene-based resin or a polyethylene-basedresin it is not necessary to select a polypropylene-based resin or apolyethylene-based resin as the mating section 3 according to whether amaterial for the innermost layer 5 of the bag 1 is a polypropylene-basedresin or a polyethylene-based resin. This makes it possible to use thepolyethylene-based resin which is softer and ensures the provision of asuperior surface finish of the bag 1. Further, when the side seals 1 a,1 b of the bag 1 are to be made as shown in FIG. 5(A) and (B), if theopposing thermally fused films 8 each for formation of a mating sectionare off from each other, this olefin-based film 8 for formation of amating section can thermally be fused and bonded to the innermost layer5 of the bag 1 at a place 8 b where the thermally fused film 8 contactsthe innermost layer 5 of the bag 1 regardless of whether a material forthe innermost layer 5 of the bag 1 is a polypropylene-based resin or apolyethylene-based resin. As such, the thermal fusion and bonding maybeperformed under stable conditions without any pin hole being generated.

[0056] In FIG. 4(A), a fourth technological factor of the presentinvention relates to further selection of a resin to be used as amaterial for the thermally fused film 7 to be thermally fused and bondedto the innermost layer 5 of the bag 1. Further a selection is made forthe thermally fused film 8 for formation of a mating section. Thepresent invention is characterized in that an olefin-based filmcomprising a resin is used in which, in addition to thepolypropylene-based resin and the polyethylene-based resin, anolefin-based rein such as polybutene or a polystyrene resin is mixedtherein as a third component. As an alternative, a resin in which, inaddition to the ethylene acetate vinyl copolymer resin and apolyethylene-based resin, an olefin-based reformer is mixed therein andis used as a third component as the thermally fused film 7 to bethermally fused and bonded to the innermost layer 5 of the bag 1 andalso as the thermally fused film 8 for formation of a mating section.

[0057] The reason for employment of the olefin-based film is, as can beappreciated from the above description, that any type of mating section3, thermally fused film 7, heat-insulating film 6 and even the thermallyfused film 8 for formation of a mating section can be used regard lessof whether a material for the innermost layer 5 of the bag 1 is apolypropylene-based resin or a polyethylene-based resin.

[0058] Thus, the zipper tape 2 according to the present invention can beused for a wide range of applications and types of the bag 1. Further,it can substantially improve the productivity in production of zippertape 2 by allowing batch production of zipper tapes 2.

EXAMPLE 1

[0059] A base tape with the width of 120 mm based on a laminatedstructure consisting of a polyethylene film 40 μm as the thermally fusedfilm 8 for formation of a mating section, a stretching polyester film 12μm as the heat-insulating film 6, and a polyethylene film 40 μm as thethermally fused film 7 to be thermally fused and bonded to the innermostlayer 5 of the bag 1 was previously prepared. Then the male strip 3 aand the female strip 3 b each made from a polyethylene-based resin wereformed in 5 rows at a prespecified space therebetween by extrusionmolding with a miscellaneous shape extrusion molding machine. These werethermally fused and bonded to the thermally fused film 8 for formationof a mating section. After temperature of the strips dropped, thethermally fused film 8 was slit along each of the male strips 3 a andfemale strips 3 b, providing a width of 12 mm along the longitudinaldirection. Each male strip was mated with each female strip respectivelywith each pair slit wound up, and thus five strips of zipper tapes 2were produced simultaneously with high productivity and excellentquality.

COMPARATIVE EXAMPLE 1

[0060] The male strip 3 a and the female strip 3 b each made from apolyethylene-based resin were produced respectively in the integratedstate with the tape section 4 to form the zipper tape 2 based on theconventional technology by means of miscellaneous shape extrusionmolding, but because of the necessity of giving a very complicated shapeand form, the male strip 3 a and the female strip 3 b could be producedonly in a pair and in a row, and it was extremely difficult tosimultaneously produce the male strips and female strips in a pair andin a plurality of rows.

EXAMPLE 2

[0061] The zipper tape 2 in Example 1 can be produced byextrusion-molding only the male strip 3 a and female strip 3 b with highstability. The weight of the mating section 3 can be reduced to theminimum level, which is a new effect provided by the present invention.The weight including that of the base tape section can be reduced toabout 5 g/m.

[0062] The zipper tape 2 according to the present invention wasthermally fused and bonded to a film for the production of bagscomprising a polyester film 12 μm, aluminum foil 9 μm, and apolyethylene film 60 μm along the longitudinal direction of each bag tobe produced, and then side sections of the bag 1 were sealed by applyinga pressure and heat thereto. As a result, a resin block including thezipper tape 2 was small, so that an excellent finish was provided to theside sections of the bag 1 and the appearance was very beautiful. Inaddition, no pin holes were generated, even if the male strip 3 a wasslightly off from the female strip 3 b.

COMPARATIVE EXAMPLE 2

[0063] The zipper tape 2 obtained in Comparative Example 1 must beproduced by extruding a large quantity of resin for the mating section 3and the tape section 4 for achieving stability in the molded state, sothat the weight of the zipper tape 2 is about 8 g/m.

[0064] This zipper tape 2 was thermally fused and bonded to a film forproduction of bags comprising a polyester film 12 μm, aluminum foil 9μm, and a polyethylene film 60 μm along the longitudinal direction ofeach bag 1 to be produced, and the side sections of the bag 1 was madeby applying a pressure and heat thereto. As a result, the resin blockcaused by the zipper tape 2 was very large, so that finishing of theside sections of the bag 1 was not so excellent with poor appearance.Further, when the male strip 3 a was slightly off from the female strip3 b, generation of pin holes was observed.

EXAMPLE 3

[0065] The zipper tape 2 produced in Example 1 was thermally fused andbonded to a film for production of bags comprising a polyester film 12μm, aluminum foil 9 μm, and a polyethylene film 60 μm along thelongitudinal direction of each bag to be produced, and the side sectionsof the bag 1 was made by applying a pressure and heat thereto forsealing. As a result, the resin block caused by the zipper tape 2 wasvery small and was easily softened and crashed, so that a load to thefilm for the production of bags was small and bags could be producedeven at the rate of 100 bags per minute without the aluminum foil beingcut.

COMPARATIVE EXAMPLE 3

[0066] The zipper tape 2 produced in Comparative Example 1 was thermallyfused and bonded to a film for production of bags comprising a polyesterfilm 12 μm, aluminum foil 9 μm, and a polyethylene film 60 μm along thelongitudinal direction of each bag to be produced, and the side sectionsof the bag 1 was made by applying a pressure and heat thereto forsealing. As a result, the resin block caused by the zipper tape 2 waslarge, and was slowly softened and hardly crashed, so that a load to thefilm for formation of bags was large and cutting of the aluminum foiloccurred at the frequency of 60 bags per minute.

EXAMPLE 4

[0067] Example 4 relates to the method of producing the zipper tape 2wherein an innermost layer of the bag is a film made from any ofethylene-acrylic acid copolymer (EAA), ethylene-metacrylic acidcopolymer metallic ion bridging resin (ionomer), and anethylene-metacrylic acid copolymer resin (EMAA), of the thermally fusedfilm and the thermally fused film for formation of a mating section, atleast the former is made from the same resin as that described above.The method is shown in the general flow diagram of FIG. 6 with themating section forming section shown in FIG. 7, and the state where themale strip 3 a and female strip 3 b are mated with each other to producethe zipper tape 2 is shown in FIG. 8. At first, a base tape 100 for awide film with the width of 72 mm based on a laminated structureconsisting of an olefin-based film 50 μm (CMPS film produced by TocelloKabushiki Kaisha) made from a resin in which, in addition to apolypropylene-based resin and a polyethylene-based resin as thethermally fused film 8 for formation of a mating section, apolybutene-based resin or the like is mixed therein as a thirdcomponent, stretching polyester film 12 μm as a heat-insulating film 6,and a polypropylene film 40 μm as the thermally fused film 7 to bethermally fused and bonded to the bag 1 was previously prepared. Themale strips 3 a and the female strips 3 b each made from apolyethylene-based resin and forming a pair respectively are alternatelymolded at a prespecified space therebetween in three rows with amiscellaneous shape extrusion-molding machine 101. The strips 3 a and 3b were thermally fused and bonded to the side of thermally fused film 8of the base tape 100, and after the male strip 3 a and female strip 3 bwere cooled in a water bath 102, the male strips 3 a and female strips 3b were cut out each with the width of 12 mm along the longitudinaldirection of the base tape 100 with a slitter 103, and then the malestrips 3 a and female strips 3 b were mated with each other one by oneto form pairs and wound up. Three strips of zipper tapes were producedsimultaneously. The reference numeral 104 in the figure indicates adrier.

[0068] This zipper tape 2 was thermally fused and bonded to a film forformation of bags comprising a polyester film 12 μm and a polypropylenefilm 60 μm along the longitudinal direction of each bag 1 to be producedand the side sections of the bag 1 was made by applying a pressure andheat for sealing. As a result, when the innermost layer of the bag 1 wasmade from a polypropylene-based resin, the bag 1 with the zipper tape 2having no sealing fault and excellent in sealing capability could beproduced even when the mating section 3 was made from apolyethylene-based resin.

COMPARATIVE EXAMPLE 4

[0069] An attempt was made to try to thermally fuse and bond thepolyethylene-based zipper tape 2 produced in Comparative Example 1 to afilm for formation of bags (with the innermost layer made from apolypropylene film). However, the zipper tape 2 could not be fused norbonded to the film for formation of bags, and therefore to enablethermal fusion and bonding, a bag with a zipper could be produced onlywith the zipper tape 2 made from a polypropylene-based resin.

EXAMPLE 5

[0070]FIG. 9 shows a zipper tape according to the present invention inwhich a base tape 101 is provided with a male strip 102 thermally fusedand bonded to a surface of the base tape 101. A female strip side basetape 103 is provided with a female strip 104 thermally fused and bondedto a surface of the base tape 103. The male strip 102 and female strip104 can freely be mated with each other or disengaged with each other.

[0071] The base tape 101, 103 has a three-layered structure in thisexample, and the outer layer (a layer which is heat-sealed to an innersurface of a bag) and an inner layer (a layer to which the male strip102 and female strip 104 are thermally fused and bonded) are formed witha polyethylene-based resin. An intermediate layer is inserted betweenthe outer layer and the inner layer and is made from a biaxialstretching polyester film. Both the male strip 102 and female strip 104are made from a polyethylene-based resin. It should be noted that thesematerials are only illustrative, and other types of films and resins maybe used according to the required function.

[0072] The reference numeral 105 indicates a remark printed on a surfacein the male strip 102 side of the base tape 101 and in the female strip104 side of the base tape 103 and indicating the necessity of “checkingthe mating state”.

[0073]FIG. 10 shows the state in which the zipper tape described aboveis fitted to inside of an upper open section 111 of a bag 110, and thebase tapes 101, 103 in the male strip side and female strip siderespectively are heat-sealed and facing to inner surfaces of the opensection 111 of the bag 110 by means of heat sealing. As indicated by thedescription above, a polyethylene film layer is formed for heat sealingon an inner surface of the bag 110 in this example.

[0074]FIG. 11 is an explanatory view showing the state where the zipperis closed and in addition the open section 111 of the bag 110 has beenclosed with a seal 112 by the heat sealing method after contents arefilled in. The reference numeral 113 indicates a V-shaped cut, and theopen section 111 of the bag 110 can be opened from this section as shownin FIG. 10.

[0075] A remark indicating the necessity of checking the mating state isprinted on an inner surface of the base tape 101 or 103 (in the matingsection). With this, when the open section 111 of the bag 110 is sealedagain, the mating state is checked to prevent unexpected accidents suchas leakage of contents from the zipper section.

[0076] By giving a specific color to the base tape 101 or 103, the colorcan visually be checked from the outside, and a user can easilyrecognize that the bag has a zipper.

[0077] Further by using different colors for the base tape 101 and basetape 103 respectively, it is possible to freely design front and backsides of the bag 110 without being restricted by the zipper, whichimproves freedom in designing.

[0078] With a further feature according to a variant of the invention,by giving different colors to the male strip 102 and female strip 104 inthe mating section respectively, it is possible for a user to visuallycheck whether the two strips have been completely mated or not bychecking changes in the colors.

EXAMPLE 6

[0079] This example 6 is illustrated in FIG. 12 and shows the statewhere a zipper tape is being produced by extruding the male strips 102and female strips 104 onto the wide base film 120 with a miscellaneousshape extrusion molding machine. In FIG. 12, a base tape film 120 isshown before being split into the base tapes 101 and base tapes 103.This base tape film 120 is fed out from the roll. The remark 105 isprinted by a cylinder 121 for printing the remark 105. Then, at thelocation of a miscellaneous shape extrusion molding machine 122, themale strips 102 and females strips 103 are alternately extruded from adie of this miscellaneous shape extrusion molding machine 122. Thesemale strips 102 and female strips 104 are thermally fused and bonded tothe base tape film 120 and then cooled by water in a cooling water bath123. Finally the base tape is slit along each strip by a slitter 124 asshown in FIG. 13 and the adjoining male strips and female strips aremated with each other by a mating machine 125 respectively and wound up.

[0080]FIG. 14 shows a state where the male strips 102 and female strips104 are colored with different colors. In such case different extrusionmolding machines 122 a and 122 b are used for molding the male strips102 and female strips 104 respectively. Resins with different coloringmaterials mixed therein are filled in the extrusion molding machines, sothat the male strips 102 and female strips 104 can thermally be fusedand bonded to the base tape 120.

EFFECTS OF THE INVENTION

[0081] As described above, the present invention is different from theconventional technology in which a male strip and a female strip areformed in the integrated state on a base tape of a zipper tape, a malestrip and a female strip are later formed by fusion bonding on a surfaceof a thermally fused film for formation of a mating section. As aresult, the following advantageous effects are provided.

[0082] 1. In production of a zipper tape, male strips and female stripscan simultaneously be formed in a plurality of rows in the state whereadjoining male strips and female strips form pairs respectively, so thatthe productivity is far higher as compared to the conventionaltechnology in which a male strip and a female strip are formed in apair.

[0083] 2. In a side seal section where zipper tapes are overlaid on eachother when a bag is formed, a resin block in the mating sectionincluding a thermally fused film for formation of the mating section issmall, which insures excellent appearance of the bag.

[0084] 3. Because the resin block is small, it is possible to overcomethe trouble caused by excessive heat applied in heat sealing, and inaddition the bag production speed can be improved.

[0085] 4. By using a specific resin film which can thermally be fusedand bonded to both a polypropylene-based film and a polyethylene-basedfilm as a thermally fused film for formation of a mating section, forinstance, it is possible to use a zipper tape having a mating sectionmade from polyethylene and this can also be used for a bag with theinnermost layer made from polypropylene.

[0086] 5. By giving or printing specific colors, marks, or letters tothe male strip and female strip for mating on a base tape of the zippertape, it is possible to check from the outside the fitted state of thezipper in a bag in which at least the zipper section is transparent orsemi-transparent.

[0087] 6. As letters, marks, and colors can be given or printed in themating section side of the base tape, this printed letters or marks canvisually be checked when the zipper tape is opened, and a remark or thelike can conveniently be printed on a surface of this base tape.

[0088] 7. By using different colors for a male strip and a female stripforming a mating section, the mated state can visually be checked whenthe two strips are mated with each other.

[0089] 8. By giving specific marks, patterns, or colors to an outersurface of the zipper tape, the colorful design of the bag can be madeeven in the zipper section.

What is claimed is:
 1. A zipper tape for a bag, the zipper tapecomprising: a male strip provide on a base tape; a female strip providedon a base tape, said male strip and said female strip being formed as amating section, wherein each base tape has at least a three-layeredstructure comprising a thermally fused film which is heat-sealed onto aninnermost layer of the bag, a heat-insulating film having a highermelting point than that of the thermally fused film laminated on asurface of the thermally fused film, and a thermally fused film forformation of a mating section laminated on a surface of theheat-insulating film, said male strip and said female strip beingextruded from a miscellaneous shape extrusion molding machine and beingrespectively thermally fused and bonded to a surface of the respectivethermally fused film for formation of said mating section.
 2. A zippertape for a bag according to claim 1, wherein both the thermally fusedfilm and the thermally fused film for formation of a mating section inthe base tape are made from a polyethylene-based resin or apolypropylene-based resin.
 3. A zipper tape for a bag according to claim1, wherein a polypropylene-based resin or a polyethylene-based resin isused for the thermally fused film in the base tape and an olefin-basedresin comprising a resin in which, in addition to thepolypropylene-based resin and polyethylene-based resin, an olefin-basedresin including one of a polybutene or a polystyrene resin is mixed as athird component, or a resin in which, in addition to an ethylene acetatevinyl copolymer resin and a polyethylene-based resin, an olefin-basedreformer is mixed as a third component is used as the thermally fusedfilm for formation of a mating section.
 4. A zipper tape for a bagaccording to claim 1, wherein olefin-based resin comprising a resin inwhich, in addition to the polypropylene-based resin andpolyethylene-based resin, an olefin-based resin such as polybutene or apolystyrene resin is mixed as a third component, or a resin in which, inaddition to an ethylene acetate vinyl copolymer resin and apolyethylene-based resin, an olefin-based reformer is mixed as a thirdcomponent is used for the thermally fused film and the thermally fusedfilm for formation of a mating section in the base tape.
 5. A zippertape for a bag according to claim 1, wherein, when an innermost layer ofthe bag is a film made from any of ethylene-acrylic acid copolymer(EAA), ethylene-metacrylic acid copolymer metallic ion bridging resin(ionomer), and an ethylene-metacrylic acid copolymer resin (EMAA), ofthe thermally fused film and the thermally fused film for formation of amating section, at least the former is made from the same resin.